BY G. I. PLAYFAIR. 347 



apices," and his figures show a plump little frustule, not at all 

 slender, elliptic-lanceolate, with sides well arched, not parallel, 

 suddenly constricted near the ends into a short rostrate apex. 

 Forms of this genus are common enough in the swamp-waters of 

 this country, but I have never yet seen them in mucous tubes. 



Var. RiCHMONDiiE, n.var. (PI. xlv., f.22.) 

 Forma fascia transversa, usque ad margines valvse non perti- 

 nente, utrinque ad nodulum centralem instructa. 

 Long. 54-58, lat. 12-14/x. 

 Lismore (185). Cum priori. 

 This form is more like those given for the type by Van Heurck. 



Vanh. cuspidata var. ambigua (Ehr.) Cleve. 



Long. 66-80, lat. 19-20, ap. 4-5 fx, 



Lismore (213, 221,253). 



Kav. ambigua Ehr., in Donkin, I.e., PI. vi., f.5. Cleve, Synop- 

 sis i., p. 109. This form is very like V. vulgaris, from which it 

 may be distinguished by its larger size, and specially by a very 

 slight angularity here and there in the arched sides. It is 

 frequent at Lismore in waterholes and swamps, and in the 

 mucous strata of the MyxophycecB. 

 Forma. 



Forma fascia transversa utrinque ad nodulum centralem in- 

 structa. 



Long. 76, lat. valv, 20, ap. 6; crass, frust. 10 /x. 



Lismore (223). 



Compare V. vulgaris var. Richmondice, supra. 



Genus Gomphonema Ag. 

 GoMPH. LANCEOLATUM var. INSIGNE Greg. (PI. xlv., f.23.) 

 Long. 62, lat. 10 /x. Striae 8 in 10 /x. 

 Lismore (185). 



Genus Achnanthes Bory. 



ACHNANTHES WoODLAWNENSIS, n.sp. (PL xlv., f.24.) 



Frustula oblonga genuflexa, zona connectente per longitudinem 

 striata, striis tenuibus 8-9. Valvse lineari-lanceolatse, in medio 

 evissime inHatae, apicibus conicis, transverse striatis. Valva 



